Master's in Genetic Counseling (MGC)

Phenylketonuria Screening in Delaware

Screening for PKU in the state of Delaware is performed by a bacterial inhibition assay (the original “Guthrie test”) to determine the level of phenylalanine in the dried blood spot. A liquid blood sample is required for diagnostic testing.

The follow-up recommendations for PKU screens in the state of Delaware are as follows:

Newborn Screening Result	Interpretation	Follow-Up Action Recommended
phenylalanine <4 mg/dl	normal	none
phenylalanine 4-8 mg/dl, >24 hours of milk feeding	abnormal result	A repeat filter paper specimen is requested within 48 hours. If the repeat specimen results are <4 mg/dl, no additional follow-up is required. If the repeat specimen results are >4 mg/dl, definitive testing is recommended within 24 hours. If definitive testing is abnormal, referral to a metabolic specialist is recommended.
phenylalanine 4-8 mg/dl, <24 hours of milk feeding	abnormal result	Definitive testing is recommended within 24 hours. If definitive testing is abnormal, referral to a metabolic specialist is recommended.
phenylalanine >8 mg/dl	abnormal result	Definitive testing is recommended within 24 hours. If definitive testing is abnormal, referral to a metabolic specialist is recommended.

NOTE: Treatment should be started as soon after birth as possible in any infant with phenylalanine levels over 8-10 mg/dl and should be continued indefinitely. Referral to a metabolic clinic is strongly recommended for assistance in definitive diagnosis, treatment, and follow-up of the disorder. Metabolic clinics are available in Philadelphia (St. Christopher's Hospital and Children's Hospital of Philadelphia) or Baltimore (University of Maryland and Johns Hopkins Hospital).

All infants with persistently abnormal levels of phenylalanine should be tested by special blood and urine tests for biopterin abnormalities.

 

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